The present invention relates to a control system for controlling the frequency of operation of aircraft radio communication and navigational apparatus.
Modern aircraft are equipped with a multitude of navigational and communication transmitters, receivers and transponders, all of which must be tuned to specific frequencies in specific areas of travel for operation. In the past, each electronic unit included its own frequency controlling means such as dials, switches, or the like which the operator of the aircraft had to individually control. Improvements over such manual tuning systems have been made where, for example, as disclosed in U.S. Pat. No. 3,701,945 issued Oct. 31, 1972, a system is provided in which a keyboard is provided for entering the desired frequency into the control system for each of the various avionics involved. This system, however, requires not only the frequency selection but also that the operator select the instrument being tuned by the frequency entered. Other prior art patents disclose a variety of methods of tuning avionic receivers or transmitters using digital controls and/or for storing information pertaining to selected frequencies. Representative of such prior art are U.S. Pat. Nos. 4,075,567; 4,119,915; and 4,122,395.